Input EMI filter for motor drive including an active rectifier

Abstract

A poly-phase motor drive includes an input EMI filter having a poly-phase filter input and a poly-phase filter output and an active rectifier connected to the filter output. The input EMI filter includes notch filters tuned at active rectifier and motor drive inverter switching frequencies and diverts common-mode current into DC bus. The active rectifier has a DC output. A motor drive inverter is connected to the DC output. The motor drive inverter has a poly-phase motor control output.

The invention claimed is: 
     
       1. A poly-phase motor drive comprising:
 an input filter having a poly-phase filter input and a poly-phase filter output, wherein the input filter includes a high-frequency common mode inductor connected to the poly-phase filter input, a plurality of common mode filter components connected to the high-frequency common mode inductor, and a differential mode damped inductive capacitance filter interconnected with the common mode filter components; 
 an active rectifier including a boost inductor, the active rectifier is connected to the filter output and has a DC output; 
 a motor drive inverter connected to the DC output, the motor drive inverter having a poly-phase motor control output; 
 wherein the differential mode filter is a T-type LC filter; 
 wherein the common mode filter components include a high frequency common mode inductor and are connected to a first shunt-type notch filter; and 
 wherein the common mode filter further comprises a first common mode choke inductor and a second common mode choke inductor, wherein said first common mode choke inductor has a first core material and said second common mode choke inductor has a second core material. 
 
     
     
       2. The poly-phase motor drive of  claim 1 , wherein said first shunt type notch filter is tuned to a switching frequency of the active rectifier. 
     
     
       3. The poly-phase motor drive of  claim 2 , further comprising a second shunt-type notch filter, and wherein the second shunt type notch filter is tuned to a switching frequency of the motor drive inverter. 
     
     
       4. The poly-phase motor drive of  claim 3 , wherein the switching frequency of the first shunt-type notch filter and the switching frequency of the second shunt-type notch filter are different frequencies. 
     
     
       5. The poly-phase motor drive of  claim 1 , wherein the first core material is a nanocrystalline material, and the second core material is a ferrite material. 
     
     
       6. A poly-phase motor drive comprising:
 an input filter having a poly-phase filter input and a poly-phase filter output; 
 an active rectifier including a boost inductor, the active rectifier is connected to the filter output and has a DC output; 
 a motor drive inverter connected to the DC output, the motor drive inverter having a poly-phase motor control output; and 
 wherein the input filter comprises: 
 a high frequency common-mode choke connected to said poly-phase filter input and having a poly-phase high frequency common-mode choke output; 
 a differential mode inductor block connected to said poly-phase high frequency common-mode choke output and having a poly-phase differential mode inductor block output; 
 a first notch filter connected to the poly-phase high frequency common-mode choke output; 
 a second notch filter connected to the poly-phase differential mode inductor block output; 
 a first common mode choke connected to the poly-phase differential mode inductor block output and having a poly-phase first common mode choke output; 
 a common mode capacitor connected to the poly-phase first common mode choke output; 
 a second common mode choke connected to the poly-phase first common mode choke output and having a poly-phase second common mode choke output; and 
 a differential mode capacitor/resistor block connected to said poly-phase second common mode choke output having an output of said poly-phase filter output. 
 
     
     
       7. The poly-phase motor drive of  claim 6 , wherein
 said first notch filter is connected to a common floating point connection via a first impedance block; 
 said second notch filter is connected to the common floating point connection via a second impedance block 
 said common mode capacitor is connected to the common floating point connection via a third impedance block 
 said differential mode capacitor block is connected to the common floating point connection via a fourth impedance block, and 
 said common floating point is connected to DC bus mid-point capacitors. 
 
     
     
       8. The poly-phase motor drive of  claim 6 , wherein
 each of said first notch filter, said second notch filter, and said common mode capacitor are connected to a floating point connection via a first impedance block; 
 said differential mode capacitor block is connected to said common floating point connection via a second impedance block; 
 said floating point connection is connected to a neutral via a third impedance block, and 
 said second impedance block is connected to DC bus mid-point capacitors. 
 
     
     
       9. A method for filtering a poly-phase motor drive comprising:
 filtering common mode noise at an input of an active rectifier by passing a received input signal through a first common mode choke constructed with a first core material and passing said received input signal through a second common mode choke constructed with a second core material different from said first core material; and 
 filtering differential mode noise at an input of the active rectifier. 
 
     
     
       10. The method of  claim 9 , wherein the step of filtering differential mode noise at the input of the active rectifier comprises filtering differential mode noise in a first frequency band corresponding to a switching frequency of the active rectifier using a first notch filter. 
     
     
       11. The method of  claim 9 , wherein the step of filtering differential mode noise at the input of the active rectifier comprises filtering differential mode noise in a second frequency band corresponding to a switching frequency of a motor drive inverter using a second notch filter.